1. Field of the Invention
The present invention relates to a filter for removal of hydrocarbons and synthetic hydrocarbons from water by adsorption and/or absorption. The filter media is contained within a casing for flow through filtration of contaminated fluids.
2. Description of the Prior Art
Contamination of water by hydrocarbons, including oils and greases, is a well-known problem. Water contamination can occur by direct leakage of hydrocarbons from storage containers, or as the byproduct of a manufacturing process, or the operation of mechanical equipment. Often as cooling water circulates through a manufacturing system hydrocarbons leak into the cooling water. Air compressors generate a waste stream of condensate that collects hydrocarbon contaminants from the air compressor lubrication systems. Diesel and gasoline engines are notorious for leaking hydrocarbons during their operation. In marine environments, particularly in boats having motors, the hydrocarbons leak from the motors and mix with the water that collects within the bilges. The U.S. Environmental Protection Agency has strict standards for the disposal of water contaminated with hydrocarbons. Most of the hydrocarbons must be removed to prevent pollution of the environment.
Since the recognition of the damage that hydrocarbons do to the environment, many systems have been developed for their removal from water and other carriers. When contaminated water contains a large quantity of immiscible hydrocarbons that are lighter than water, skimming is effective as a first step in separating the hydrocarbons from water, but skimming is ineffective for removal of light contamination. After skimming is completed, the contaminated water must be treated further, as skimming Leaves too much contamination.
Sand filters have been used to remove hydrocarbons from water, but they have a number of problems. Most sand filters are too fine to permit oil to penetrate the filter resulting in rapid plugging through agglomeration of the oils with the filter media. A bed of larger granules of sand opens the filter bed for penetration of the contaminants, reducing the agglomeration but then the sand filters do not efficiently collect the contaminants.
Bed type filters using dual media are also known. These filters have a first upper layer of large granular material and a second lower layer of fine granules. The layer of the large granular media opens the top surface of the bed to permit the penetration of suspended contaminants deeper into the bed for access to the second layer of fine sand, but agglomeration still occurs reducing the efficiency of the filter bed.
U.S. Pat. No. 5,207,895 discloses a complex Oil/Water Separator that uses vertical columns of coalescing media fabricated from polypropylene. The coalescing media causes the oil to join together to float on the top of water, so that the layer of oil can be drawn off for disposal.
Various materials have been effectively used to collect hydrocarbons through absorption or adsorption. These materials are often used to contain oil spills and to clean the oil from the top of the water surface and from beaches. The material is formed into long booms and placed into the water to restrict the movement of the oils floating on the water and to trap the oils that come into contact with the boom through absorption or adsorption. The material is very effective on its surface, but the oil collects close to the surface of the boom without penetrating, preventing full utilization of the material. For cleanup purposes the material is used in relatively thin sheets. Using these materials as filter media for a flow through filter has been unacceptable due to plugging of the passageways in the first three inches or so of the filter media, and due to channeling through the media that permits the contaminated water to flow through the filter without contacting fresh media for effective reduction of the hydrocarbons carried therewith.
One method to overcome the plugging of the filter media is disclosed by the patent to Lohri et al, U.S. Pat. No. 5,328,598, which discloses a filter having three layers of an adsorption media that are divided by a pair of spaced apart plates that extend radially to the longitudinal axis of the jacket, across the filter casing sealing the filter media into three separate compartments. A plurality of narrow bores or tubules are formed through these plates for the passage of contaminated water from one filter layer to the next.
Not withstanding the existence of many prior art methods for separating hydrocarbons from water, it remains clear that there is a need for a simple flow-through filter. Such filters can be used in many locations, but are particularly suited for the marine environment where the water in the vessels bilges; is contaminated with hydrocarbons and yet the water must be removed from the vessel. The hydrocarbons must be removed from the water in the bilges so that the water meets the established standards, before the water is returned to the environment. The oil must be collected by a filter media for later disposal.